The development of Type 2 diabetes (T2DM) in adults results from the gradual fall in p-cell function occurring on a background of insulin resistance. The inclusion of pediatric participants in studies envisioned by this RFA is critical because there are subtle but important differences in T2DM pathophysiology in adolescents, particularly with regard to changes in beta-cell function. Indeed, the deterioration in beta-cell functio in youth with T2DM is accelerated relative to than that observed in adults. Furthermore, in childhood, the beta-cell secretory burden to compensate for insulin resistance grows disproportionately larger when insulin resistance worsens during puberty. Diminished first-phase insulin secretion is an early marker of beta-cell dysfunction, appearing long before significant changes in absolute glucose concentrations are apparent in obese youth. Declining beta-cell function relative to insulin sensitivity in these obese youth is evident with increasing fasting glucose levels even in the non-diabetic normal range. The central theme of our proposal is that desensitization of the beta-cell to changes in glucose levels and beta-cell destruction due to glucolipotoxicity may contribute to alterations in insulin secretion. Early correction of glucotoxicity via early intensive insulin therapy, allowing beta-cell rest, may be a strategy to protet or produce sustained recovery of beta-cell function in youth with new onset T2DM. Therefore, we hypothesize that early intensive intravenous insulin infusion (IVII) plus metformin in youth with recently diagnosed T2DM, by tightly controlling fasting and postprandial hyperglycemia, will have favorable effects on short-term recovery and long-term maintenance of p-cell function (first phase insulin secretion) and long-term glycemic control compared with treatment with metformin alone. To address this hypothesis, we have brought together 3 centers of Pediatric Endocrinology/Metabolism and Diabetes Mellitus with expertise in adolescent T2DM to determine: whether a short course of early IVII plus metformin in obese adolescents with new onset T2DM, to rapidly attain fasting and post-parandial normoglyemia, can restore short-term insulin secretion, sustain the recovery of long-term insulin secretion, and promote extended and durable glycemic control relative to metformin therapy alone.